1. Field of the Invention
The present invention relates to a frame handling system and frame handling method used therefor, particularly to a frame handling system and frame handling method whereby it is possible to dynamically handle frames depending on instructions from a segmentation and reassembly (SAR) portion.
2. Description of the Prior Art
It is necessary for a conventional frame handling system and frame handling method therefor to handle frames appropriately according to the type of multiple input lines, for example, according to the connection types such as VP connections and VC connections, or to the class of traffic such as CBR (constant bit rate) lines for digitized voice and images, VBR (variable bit rate) lines for voice in packets, and best effort type UBR (unspecified bit rate) lines, its frame handling portion seeks and adopts an appropriate handling method based on information regarding VP and VC connections, class of traffic, and state of involved lines received from its SAR portion together with frames.
However, with the conventional frame handling system and method therefor as described above, the frame handling portion must seek an appropriate handling method based on information regarding VP or VC connection, in addition to the information of frames to be handled, and thus it needs a search function before it can determine how handling should be made. This forms a problem.
Further, it must search through the data in frames before it proceeds to handling of the frames, which will require a time which would be otherwise unnecessary.
This invention aims at providing a frame handling system and frame handling method therefor in which a frame handling portion placed behind an SAR portion, when handling frames received through lines of VP or VC connection and of different classes of traffic, is capable of speedily handling the frames appropriately according to the type of lines, requiring a minimum function/circuit involvement.
This invention particularly aims at providing a frame handling system and frame handling method therefor in which a frame handling portion to handle frames in upper layers and placed behind SAR portion of ATM adaptation layer 5 (AAL5) dynamically handles frames appropriately according to the type of frames, altering the mode of frame handling depending on information provided by the SAR portion.
To achieve the above object, the present invention provides a frame handling system to apply frame handling to a stream of ATM cells received through communication lines comprising a cell segmentation and reassembly (SAR) portion and a frame handling portion, wherein the SAR portion comprises a frame forming portion to separate the information part from the header part for each of ATM cells received through communication lines and to form a frame based on the information, and a frame handling mode setting portion to provide data for frame handling in accordance with the information part isolated by the frame forming portion, the handling data being attached to the frame to be delivered to the frame handling portion, while the frame is being formed by the frame forming portion.
In addition, the present invention provides a frame handling system wherein the frame handling portion comprises a frame handling mode selecting portion which selects a frame handling mode in accordance with the handling data attached to the frame delivered by the SAR portion, a handling portion to achieve frame handling as selected by the frame handling mode selecting portion, and a frame handling result returning portion which returns the result of frame handling achieved by the handling portion to the SAR portion together with the handled frame.
In addition, the present invention provides a frame handling system wherein the SAR portion comprises a routing portion which routes a frame in accordance with the instruction returned by the frame handling result returning portion, and a frame handling executor to handle a frame in accordance with the instruction routed by the routing portion.
In addition, the present invention provides a frame handling system wherein the frame handling executor comprises a cell reassembling portion to reassemble cells when the instruction for frame handling notifies transmission through communication lines, a discarding portion to discard the handled frame when the instruction notifies disposal, and a delivery-to-processor portion to deliver the handled frame to a processor when the instruction notifies delivery to a processor.
In addition, the present invention provides wherein, when the instruction routed by the routing portion notifies transmission through communication lines, the handled frame with a transmission virtual path (VP) or transmission virtual channel (VC) attached thereto is delivered to the cell reassembling portion.
In addition, the present invention provides a method suitable for a frame handling system comprising an SAR portion and frame handling portion to handle frames after having received a stream of ATM cells through communication lines comprising a signal reception step of receiving a stream of ATM cells through communication lines, a segmentation step of separating the information part from the header part for each of ATM cells received during the signal reception step, a frame handling mode setting step of introducing data for frame handling in accordance with the information part separated in the segmentation step, a frame forming step of forming a frame by attaching the handling data introduced in the frame handling mode setting step to the frame, a frame handling mode selecting step of selecting the handling data attached to the frame formed during the frame forming step, a frame handling step of achieving frame handling in accordance with the data selected during the frame handling mode selecting step, a frame handling instruction returning step of returning an instruction for frame handling to the SAR portion, together with the frame handled in the frame handling step, a frame routing step of routing the frame in accordance with the frame handling instruction returned during the frame handling instruction returning step, a cell reassembling step of reassembling cells when the frame handling instruction notifies delivery thorough communication lines, and a signal transmission step of transmitting, through communication lines, cells reassembled during the cell reassembling step, which is further provided with a discarding step of discarding the frame whenever the instruction received during the frame routing step notifies disposal, and a delivery-to-processor step of delivering the frame to a processor whenever the instruction received during the frame routing step notifies delivery to a processor.